1. Field of Invention
The present invention relates generally to 3D photography, and more specifically to a multi-lens camera for taking a plurality of 2D images at different viewing angles wherein the spacing between lens apertures are adjustable to control the parallax.
2. Prior Art
In lenticular 3D photography, the basic process involves taking a plurality of two-dimensional (2D) images of a scene from a number of horizontally-spaced vantage points and exposing these 2D views on a lenticular print material at different projection angles to compose a 3D print. The most convenient way to take a number of 2D images of a scene is to use a camera having multiple taking lenses so that the views at different vantage points can be simultaneously captured.
Because 2D images are captured at different vantage points, they are slightly different one from another. The difference between 2D images, or the parallax, is due to the fact that the photographed objects in a scene are located at significantly different distances from the camera. The parallax in 2D images directly affects the quality of the composed 3D photograph. If the parallax is too little, then the 3D effect is poor. If the parallax is excessive, then the viewer may have difficulty in fusing together two 2D views of a stereo pair. Thus, it is essential to control the parallax when one takes the 2D views of a scene to ensure a good 3D effect on the composed 3D print. It should be noted that parallax in the 2D images is directly proportional to the distance between the horizontally-spaced vantage points.
In the past, a number of patents have disclosed multi-lens cameras for 3D photographic applications. U.S. Pat. No. 4,086,585 (Wah Lo et al.) discloses a multi-lens camera wherein the lens spacing is fixed; U.S. Pat. No. 4,800,407 (Wah Lo) discloses a 3D camera having three fixedly located lenses to provide 2D images for composing 3D photographs with a wider range of viewing angles; U.S. Pat. No. 4,475,798 (Smith) discloses a plural lens camera wherein the spacing between lenses is also fixed but each lens is independently adjustable so that the optical axes of the lenses can be made substantially parallel in a first plane and substantially coplanar in a second plane orthogonal to the first plane.
Using a multi-lens camera with a fixed lens spacing, one cannot control the parallax when taking a plurality of 2D images of a scene. Consequently, unless the objects in a photographed scene are located at proper distances, the parallax in the 2D images may be too little or excessive. U.S. Pat. No. 3,953,869 (Wah Lo et al.) discloses a camera with a plurality of taking lenses arranged in a straight path wherein the spacing between taking lenses is adjustable. A camera with adjustable lens spacing allows a photographer to control the parallax by moving the taking lenses in the horizontal directions thereby shortening or lengthening the spacing between those taking lenses. However, in order to keep the field of view of a taking lens unchanged, when the lens is moved, the image frame defining the boundary of the image formed by the same taking lens must also be moved by the same distance. Consequently, there are a number of major disadvantages associated with a multi-lens with adjustable lens spacing including: 1) the minimum spacing between two taking lenses is confined to the spacing between two image frames. As shown in FIG. 1 which depicts a prior art two-lens camera with adjustable lens spacing, the spacing D between the two taking lenses cannot be further reduced because the two image frames cannot be moved closer; 2) substantial film areas are unused and therefore wasted to allow for the moving of image frames; and 3) that the spacing between image frames on film is variable will certainly add complexity to the 3D image composing process.
It is an advantage to have a multi-lens 3D camera wherein parallax can be controlled over a reasonably large range while the image frames on film remain fixed in relation to each other.
The following U.S. Patents are also disclosed as of interest: U.S. Pat. No. 3,852,787 (Nims et al.), U.S. Pat. No. 3,960,563 (Loet al.), U.S. Pat. No. 4,037,950 (Loet al.), U.S. Pat. No. 4,063,265 (Loet al.) and U.S. Pat. No. 4,086,585 (Loet al.).